I once recorded the "Devil's Chain" spell in Chaos magic....
When used, the spell did nothing (no damage), so I haven't changed the magic since.

Yes, I've looked into this a bit, and it's disappointing. Based on the updated understanding of the task, here are some new questions.

1) Are the spells learned in "Tomes" and "Grimoires" defined somewhere? Or can't we influence this?

2) Since I started adding new heroes, I encountered a problem with their availability. It turns out that they weren't "unlocked" on previously created and original maps, so I can't select or hire them in the tavern.
The question is, is there a way to influence these settings globally, and/or is there a way to change the "default" hero access settings for maps?